Numerical Research on The Stability of Launching Devices During Firing

An important problem in studying the sloped rocket launch is to determine the oscillations and their effects on the initial conditions of the rocket path. Tiffs phenomenon influences the stability of the launching device and the firing precision. It is assumed that the launching device and the moving rocket form a complex oscillating system that join togefller into a sum of rigid bodies botmd by elastic elements （the vehicle chassis, the tilting platform and the rockets in the containers）. The calculations of the launching device oscillations during the launch by numerical methods are presented.     

Research on Simulation of Langlie Method Test of Fuze Arming Distance

In mathematically statistical test methods that were used to get arming distance of fuze, Langlie method has been widely applied because it only use a few samples. Monte-Carlo method was used to simulate and calculate Langlie method test of fuze arming distance by using computer. The result shows that the larger error and scatter exist in the esti- mate of arming distance variance although 50% response level of arming distance can be estimated using a little sample; the correction coefficient of variance estimate can be got by simulating and calculating, but it is useless to a certain single test; this means that a larger error exists when Langlie method test is used to get the muzzle safety distance and the arm- ing distance of fuze, and the maximum arming distance becomes shorter and the minimum one longer without correcting.     

Research on Key Technologies of Detecting 1553B Avionics Data Bus Network

1553B avionics data bus network may fail due to vibration, temperature, humidity or human error. Therefore, the research on detection technology of 1553B avionics data bus network is an important subject. The key technologies are studied by analyzing the possible faults of the network, including four-wire DC resistance measurement method for conductors-to-shield short test and stub continuity test, equivalent impedance measurement of coupling transformer for main bus continuity test, polarity reversal test base on duty ratio measurement, attenuation measurement base on coupler model, and data path integrity test base on bit error rate calculati~,,. Finally, the implementation methods of key technologies are researched, a portable integrated automatic test system of 1553B data bus network is constructed based on PC 104 computer, and the hardware configuration and test process are especially designed.     

Collaborative Error Registration Algorithm for Radar System

Affected by common target selection, target motion estimation and time alignment, the radar system error reg- istration algorithm is greatly limited in application. By using communication and time synchronization function of a data link network, a collaborative algorithm is proposed, which makes use of a virtual coordinates constructed by airplane to get high precision measurement source and realize effective estimation of the system error. This algorithm is based on Kalman filter and does not require high capacities in memory and calculation. Simulated results show that the algorithm has better convergence performance and estimation precision, no constrain on sampling period and accords with transfer characteristic of data link and tactical internet perfectly.     

Biased retro-proportional navigation law for interception of high-speed targets with angular constraint

A new guidance law, called biased retro proportional navigation （BRPN）, is proposed. The guidance law is designed to intercept high-speed targets with angular constraint, which can be used for ballistic target interception. BRPN guidance law is defined, and the exact time-varying bias for a required impact angle is derived. Furthermore, the simulation results （trajectory, variation of navigation ratio, capture region, etc） are compared with those of biased proportional navigation （BPN）, proportional navigation and retro-proportional navigation. The results show that, at the cost of a higher intercept time, BRPN demands lower terminal lateral acceleration and has larger capture region compared to BPN.     

First-principles Study of Electronic Structures,Elastic Properties and Thermodynamics of the Binary Intermetallics in Mg-Zn-Re-Zr Alloy

The electronic structures, elastic properties and thermodynamics of MgZn2, Mg2Y and Mg2La have been determined from the first-principle calculations. The calculated heats of formation and cohesive energies show that MgzLa has the strongest alloying ability and structural stability. The structural stability mechanism is also explained through the electronic structures of these phases. The ionicity and metallicity of the phases are estimated. The elastic constants are calculated; the bulk moduli, shear moduli, Young＇s moduli, Poisson＇s ratio value and elastic anisotropy are derived; and the brittleness, plasticity and anisotropy of these phases are discussed. Gibbs free energy, Debye temperature and heat capacity are calculated and discussed.     

Research on design and firing performance of Si-based detonator

For the chip integration of MEMS （micro-electromechanical system） safety and arming device, a miniature detonator needs to be developed to reduce the weight and volume of explosive train. A Si-based micro-detonator is designed and fabricated, which meets the requirement of MEMS safety and arming device. The firing sensitivity of micro-detonator is tested according to GJB/z377A-94 sensitivity test methods： Langlie. The function time of micro-detonator is measured using wire probe and photoelectric transducer. The result shows the average firing voltage is 6.4 V when the discharge capacitance of firing electro-circuit is 33 μF. And the average function time is 5.48 μs. The firing energy actually utilized by Si-based micro-detonator is exD10red.     

Estimation of the kinetic parameters for thermal decomposition of HNIW and its adiabatic time-to-explosion by Kooij formula

A differential/integral method to estimate the kinetic parameters （apparent activation energy Ea and pre-exponential factor A） for thermal decomposition reaction of energetic materials based on Kooij formula are applied to study the nonisothermal decomposition reaction kinetics of hexanitrohexaazaisowurtzitane （HNIW） by analyzing nonisothermal DSC curve data. The apparent activation energy （Ea） obtained by the integral isoconversional non-isothermal method based on Kooij formula is used to check the constancy and validity of apparent activation energy by the differential/integral method based on Kooij formula. The most probable mechanism function of thermal decomposition reaction of HNIW is determined by a logical choice method. The equations for calculating the critical temperatures of thermal explosion （T_b） and adiabatic time-to- explosion （t_Tlad） based on Kooij formula are used to calculate the values of Tb and t_Tlad to evaluate the thermal safety and heat-resistant ability of HNIW. All the original data needed for analyzing the kinetic parameters are from nonisothermal DSC curves. The results show that the kinetic model function in differential form and the values of E_a and A of decomposition reaction of HNIW are 3（1 - α）[-ln（1 - α）]2/3, 152.73 kJ mol 1 and 10~11.97 S 1, respectively, and the values of self-accelerating decomposition temperature （T_SADT）, Tb and t_Tlad are 486.55 K, 493.11 K and 52.01 s, respectively.     

Calculation Method and Analysis of Blockage Time of Cluster Munitions Against Runway

The blockage probability and the blockage time are two important indexes for assessing the blockage efficiency of cluster munitions against the runway. The improved region-by-region searching method and the random sampling method are proposed to calculate the blockage time by considering the minimum number of craters which need to be re- paired after attack. A minimum leave window （MLW） with the minimum number of craters is found out as a region to be repaired, the blockage probability and the blockage time are calculated by the two methods in which the impact points of the sub-munitions are generated with Monte-Carlo simulation technique. An example is given to show the reasonableness of the two methods under the conditions of adequacy simulating times and enough sampling times, and how to choose the methods in application.     

Effect of welding processes and consumables on fatigue crack growth behaviour of armour grade quenched and tempered steel joints

Quenched and Tempered （Q＆T） steels are widely used in the construction of military vehicles due to its high strength to weight ratio and high hardness. These steels are prone to hydrogen induced cracking （HIC） in the heat affected zone （HAZ） after welding. The use of austenitic stainless steel （ASS） consumables to weld the above steel was the only available remedy because of higher solubility for hydrogen in anstenitic phase. The use of stainless steel consumables for a non-stainless steel base metal is not economical. Hence, alternate consumables for welding Q＆T steels and their vulnerability to HIC need to be explored. Recent studies proved that low hydrogen ferritic steel （LHF） consumables can be used to weld Q＆T steels, which can give very low hydrogen levels in the weld deposits. The use of ASS and LHF consumables will lead to distinct microstructures in their respective welds. This microstructural heterogeneity will have a drastic influence in the fatigue crack growth resistance of armour grade Q＆T steel welds. Hence, in this investigation an attempt has been made to study the influence of welding con- sumables and welding processes on fatigue crack growth behaviour of armour grade Q＆T Steel joints. Shielded metal arc welding （SMAW） and Flux cored arc welding （FCAW） were used for fabrication of joints using ASS and LHF consumables. The joints fabricated by SMAW process usin~ LHF consumable exhibited superior fatigue crack growth resistance than all other joints.     

A New Micro-magnetism Sensor Based on Giant Magneto-impedance Effect and Multivibrator Bridge

A novel sensor for micro-magnetic field detection is proposed based on the physical characteristics and giant magnetco-impedance （GMI） effect of Fe-Co-Si-B amorphous wires. The sensor circuit ensures high sensitivity, high detection precision, fast response and small power consumption. The signal processing circuit taking complex pro- grammable logic device （CPLD） as core chip not only improves the identification ability for pseudo ferromagnetic objects, but also ensures the real-rime response. It is the foundation for the proposed sensor to serve widely in military and civil. By using its high sensitivity for geomagnetism variation, as an application example, the sensor is used to compare and analyze different cars.     

A Simulation Study of the Turbulent Drag Reduction Mechanisms Derived from Shark Skin

Through the numerical simulation investigation, the turbulent drag reduction mechanisms of shark riblet surface are explored. In allusion to the characteristics of riblets surface, the computation region, grids and flow parameters are dealt with reasonably. These present simulation results show preliminarily that 1） only the near-wall flow field above riblet surfaces is affected by riblets, and the flow within riblets is slow and quiescent; 2） the viscous sub-layer above riblet surface is thicker; 3） the shear stress and the local friction coefficient above the riblet surface are reduced, and the drag reduction quantity is larger at the bottom of riblets than that at the top. Numerical simulation investigation on the riblet surface in the paper can provide a reference for future research in this field.     

A Magnetic Disturbance Compensation Method Based on Magnetic Dipole Magnetic Field Distributing Theory

The interference of carrier magnetic field to geomagnetic field has been a difficult problem for a long time, which influences on the deviation of navigation compass and the error of geomagnetic measurement. To increase the geomagnetic measuring accuracy required for the geomagnetic matching localization, the strategy to eliminate the effect of connatural and induced magnetic fields of carrier on the geomagnetic measuring accuracy is investigated. The magnetic- dipole＇s magnetic field distributing theory is used to deduce the magnetic composition in the position of the sensor installed on the carrier. A geomagnetic measurement model is established by using the measuring data with the ideal sensor. Con- sidering the magnetic disturbance of carrier and the error of sensor, a geomagnetic measuring compensation model is built. This model can be used to compensate the errors of carrier magnetic field and magnetic sensor in any case and its parame- ters have clear or specific physical meaning. The experimented results show that the model has higher geomagnetic mea- suring accuracy than that of others.     

Microstructural Evolution and Mechanical Properties of AZ31 Magnesium Alloy Prepared by Casting-solid Extrusion Forging During Partial Remelting

The casting-solid extrusion forging plus semi-solid partial remelting route is used to improve the properties of AZ31 magnesium alloy products. The effect of remelting temperature and holding time on the microstructure of AZ31 magnesium alloy is studied. Furthermore, the properties of AZ31 magnesium alloy components produced by the casting-solid extrusion forging plus partial remelting route are examined. The results show that the AZ31 components have very good smooth surface and are formed completely. The increases in holding time and remelting temperature result in the formation of spheroidal grains surrounded by liquid phases. The best combination of properties of thixoforged alloy is 290 MPa of tensile strength, 220 MPa of yield strength and 10% of percentage elongation.     

Dynamic Fracture Behaviors of Selected Aluminum Alloys Under Three-point Bending

The dynamic fracture behaviors of the extraded 2024-T4 mad 7075-T6 aluminum alloys are investigated by using an instranaent ed di＇op tower machine. The specimens are made fi＇om a 25 irma diameter extraded circular rod. The dynamic three-point bending tests of each alloy are canied out at different impact velocities. The initiation fracture toughness mad average propagation fracture toughness of 2024-T4 mad 7075-T6 are determhaed at different loading rates. The results show that both the initiation toughness mad the propagation toughness increase with the loading rate. Fmther, the difference between the fracture toughness behaviors of 2024-T4 mad 7075-T6 is found to be dependent on the variation of fl-acVcu-e mechanism. The comprehensive fract ograpinc investigations of the fracture surfaces clearly demonstrate that the fracture mode of 2024- T4 is predominmatly transgramular fracture with high density small-sized dimples, mad the fracture mode of 7075-T6 is mainly intergramaular fracture with many intemaetalllc particles in the bottom of voids located in the fracture surface.     

A Failure Sample Selection Method Based on Failure Pervasion Intensity

The complex and uncertain relationship among failures was always ignored in failure sample selection based on traditional testability demonstration experimental method. A failure pervasion model is founded based on fuzzy probability Petri net （FPPN） which can depict the propagation and pervasion relation among failures, then failure pervasion intensity is defined, the process of failure pervasion was depicted based on k-step fault pervasion algorithm and the pervasion inten- sity was expressed by a value. The method of sample selection based on failure pervasion intensity and failure rate is intro- duced into the process of sample selection. The practical application shows that the sample set selected based on failure pervasion intensity and failure rate can represent the failure set adequately.     

Minimum Curvature Design of turbine Hydrodynamic Three-Element Centripetal- Torque Converters

The influence of streamline bending inertia force on power loss is investigated. In order to analyze the combined effect of the inertia force and the path on the power loss, the accumulation effect expression of the inertia force on its path is derived. The calculation result shows that the accumulation effect of the unit inertia force on its path depends merely upon the velocity magnitude and the path scroll angle. As long as they are given, the accumulation effect is a constant and independent of the intermediate path. An important conclusion drawn is that the maximum inertia force rather than its ac- cumulation effect plays a predominant role in the power loss. Thus, a new design method, minimum streamline curvature method, is proposed. Fluid particle movement inside a hydrodynamic torque converter can be regarded as curved move- ment on the circular surface and decomposed into a meridional component and a circumferential component. Each merid- ional streamline is designed to be close to a circular arc, while each torus streamline is constructed with a circular arc and a straight line segment. Based on the meridional streamline equation, the torus streamline equation and a streamlined thickness function, a blade surface equation of three-element centripetal-turbine hydrodynamic torque converter can be obtained.     

Application of Space-time Conservation Element and Solution Element Method in Intake and Exhaust Flows of High Power Density Diesel Engine

A one-dimensional pipe flow model of single-cylinder diesel engine is established to investigate the intake and exhaust flow characteristics of diesel engine in the condition of high power density （HPD）. A space-time conservation element and solution element （CE/SE） method is used to derive the discrete equations of the partial differential equation for the intake and exhaust systems. The performance parameters of diesel engine with speed of 2100 r/min are simulated. The simulated results are in accordance with the experimental data. The effect of increased power density on charging coefficient is analyzed using a validated model. The results show that the charging coefficient is slowly improved with the increase in intake pressure, and is obviously reduced with the increase in engine speed.     

Analysis of Micro-scale Flame Structure of AP/HTPB Base Bleed Propellant Combustion

A complex multiple flame stracture is formed dining the combustion of AP/HTPB base bleed propellant. The AP monopropellant flame is concentrated in a thin zone above the burning surface of AP mystal to maintain seK-sustained decomposition. Due to the low temperature near the burning surface, the diffusion between the decomposition products of AP and the pyrolysis products of HTPB occurs, and a partly pre-mixed diffusion flame stracture-leading edge flame （LEF） is formed. The effects of pressure, chemical reaction rate and AP particle size on diffusion flame structure in the ravage from 20 arm to 100 ann are discussed. The Peclet number increases from 6.64 at 20 ann to 21.91 at 100 ann when AP particle size is 140 μm. The high temperature zone is blown away from the burning surface because the convective transport rate increases with the increase in Peclet number. The chemical reaction rate is enhanced and the diffusion mixing is hlhibit ed as Damkolfler nunlber increases. The chemical heat release is more concentrated axed the chemical reaction zone becomes nan＇ow when Damkolfler nunlber changes from 330 at 20 ann to 4700 at 100 atm. When AP particle diameter is decreased to 60 μm, the diffusion time scale is reduced due to the reduced diffusion length scale. So the diffusion mLxing is enhanced a more pre-mixed flame is formed. The burning rate increases because the more pre-mixed     

Interaction and Compatibility Between DAAzF and Some Energetic Materials

The interaction and compatibility between diaminoazofuraz （DAAzF） and some energetic materials are studied by using pressure differential scanning calorimetry （DSC） method. The energetic materials include cyclotetramethylenetetranitramine （HMX）, cyclotrimethylenetrinitramine （RDX）, nitrocellulose （NC）, nitroglycerine （NG）, 125/100--NC/NG mixture （NC ＋ NG）, N-nitrodihydroxyethylaminedinitrate （DINA）, aluminum powder （A1）, and 3,4-dinitrofurzanfuroxan （DNTF）. The results show that there are obvious interactions between DAAzF and DNTF, DINA, HMX or RDX, while weak interactions between DAAzF and NC, NG, NC ＋ NG or A1. According to the evaluated standard of compatibility, the binary systems of DAAzF with NC, NG, NC ~ NG and A1 are compatible, the binary system of it with RDX is slightly sensitive, the binary systems of it with HMX and DINA are sensitive, and the binary system of it with DNTF is hazardous. Copyright 2013, China Ordnance Society. Production and hosting by Elsevier B.V. All rights reserved.